FIG. 1 illustrates a concept of scalable video coding (SVC).
Referring to FIG. 1, in SVC, a plurality of video layers are coded into a single bit string.
An SVC layer is constructed with a base layer and one or more enhancement layers stacked on the base layer.
Each enhancement layer can represent the maximum bit rate, frame rate, and resolution based on information about a lower layer.
In the SVC, as the number of sequentially stacked enhancement layers increases, various bit rates, frame rates, and resolutions can be supported.
The SVC is a coding technique capable of solving problems pertaining to a variety of bandwidths occurring in heterogeneous network environments, a variety of performances and resolutions of receiving terminals, a variety of preferences of content consumers, and the like.
FIG. 2 illustrates a format of a multimedia file.
In general, when a video content is desired to be stored as a file, metadata about a coding method, contents, and any access information for the content are separately stored so as to secure free access to any location of the content and to easily reprocess the content, in addition to media data of the content.
In addition, a unit of track is defined as a unit of a medium which is continuously reproducible.
Referring to FIG. 2, a multimedia file is stored as a structure having an audio track and a video track.
When the video content is coded into an SVC format, the multimedia file may have two or more video tracks, due to a feature of SVC.
FIG. 3 illustrates scalable layers of SVC coded content.
The SVC has a feature of coding a plurality of video layers into a single bit string.
Referring to FIG. 3, a scalable base bit-stream is a single bit-stream (p1 to pm) having the highest image quality. The scalable base bit-stream includes the total coded data 310.
A sub bit-stream (to-be-transmitted coded data a which ranges from 0 to a, or to-be-transmitted coded data b which ranges from 0 to b) can be freely generated according to a bandwidth supported by a network or a specification of a user terminal.
A sub bit-stream a 320 includes the to-be-transmitted coded data a. A sub bit-stream b 330 includes the to-be-transmitted coded data b.
A scalable base bit-stream, a sub bit-stream a and a sub bit-stream b are constructed with one or more scalable layers p1 to pi.
The scalable base bit-stream includes all the scalable layers p1 to pi.
The other sub bit-streams include scalable layers having a specific range (sub bit-stream a includes scalable layers p1 to pi, or sub bit-stream b includes scalable layers p1 to p3).
FIG. 4 illustrates a format of an SVC file in which SVC coded content is stored.
Referring to FIG. 4, the scalable base bit-stream and the sub bit-stream can be respectively constructed with separate tracks, which are generally referred to as a scalable base track and a sub track.
In this case, two or more video tracks may be included in a file. When two or more video tracks are included in a file, metadata for representing scalable layers may be separately included in the file according to the tracks.
Conventionally, when SVC coded content is stored in a file, {circle around (1)} data is repeated and duplicated in the common parts of the metadata of tracks, and {circle around (2)} a relation of the tracks correlated to one another cannot be represented.